In research reported about 20 years ago, Happy appeared to recognize herself in a mirror. She was later the subject of a failed lawsuit claiming elephants should have certain fundamental human rights Happy in her enclosure in 2022 Photo by Andrew Lichtenstein via Getty Images Happy, an Asian elephant who had lived at the Bronx Zoo since 1977, was euthanized on May 26 after a period of declining health. She was renowned for both her contributions to science and for her role in legal wrangling over the rights of animals. Recent veterinary evaluations suggested Happy’s kidneys and liver were declining. And a necropsy, the animal version of an autopsy, performed this week revealed she had several large, inoperable uterine tumors, along with arthritis. “Making the decision to euthanize an animal is one of the hardest and most heartbreaking responsibilities in animal care, requiring immense compassion and love for the animal,” says  Craig Piper , interim director of the Bronx Zoo, in a  statement .…